1. Field of the Invention
The present invention relates to a ceramic electronic component and a wiring board including a built-in ceramic electronic component including the same.
2. Description of the Related Art
In recent years, with the reduction in the size and thickness of electronic devices, such as cellular phones and portable music players, a reduction in the size and thickness of wiring boards which are installed in such electronic devices has also been advancing.
Japanese Unexamined Patent Application Publication No. 2002-100875 proposes a method for reducing the thickness of a wiring board, in which a ceramic electronic component is embedded in a wiring board, and an interconnect line to the ceramic electronic component is formed by a via-hole electrode disposed on the ceramic electronic component. In this method, it is not necessary to secure a region in which a ceramic electronic component is disposed on the surface of a wiring board, and also it is not necessary to secure a region in which an interconnect line to the ceramic electronic component is provided separately from a region in which the ceramic electronic component is provided. Consequently, it is possible to reduce the size of a wiring board having a built-in component.
As described in Japanese Unexamined Patent Application Publication No. 2002-100875, the via-hole electrode is formed by Cu plating in many cases. Therefore, in view of improving connectivity between the via-hole electrode and an outer electrode of the ceramic electronic component, the outermost layer of the outer electrode is preferably composed of Cu.
In general, a via-hole electrode is provided in a via hole which is formed by irradiation with a laser, such as a CO2 laser, toward a position at which an outer electrode of a ceramic electronic component is located in a wiring board. There is a possibility that the outer electrode will be melted by being heated during laser irradiation.
In particular, in a thin ceramic electronic component in which a thin outer electrode is provided in order to reduce the thickness of a wiring board, the problem of melting of the outer electrode during laser irradiation is likely to occur.